1. Field of the Invention
The present invention relates to a high-voltage lamp-ignition technology, particularly to a high-voltage lamp-ignition piezoelectric oscillator.
2. Description of the Related Art
The principle of CCFL (Cold Cathode Fluorescent Lamp) is similar to that of the daylight lamp. When a high voltage is input to the electrodes, few electrons impact the electrode at high speed to generate secondary electrons. Then, discharge begins, and electrons collide with mercury atoms, and the mercury atoms radiate ultraviolet ray with a wavelength of 253.7 nm. Then, the ultraviolet ray excites the fluorescent powder on the inner tube wall to emit visible light with the correlated color temperature. In addition to be used in display devices, PDA, digital cameras, mobile phones, etc., CCFL is also an indispensable element for backlight modules. CCFL does not use a lamp filament and thus is free from the problem of filament burnout; therefore, CCFL has a reliable lifetime. CCFL has the advantages of a small tube diameter, high light efficiency, high brightness, low temperature and a long service life when it is used as a light source.
To achieve a small size and a superior electric performance, the coil-type step-up transformer is replaced by a piezoelectric transformer in the ignition circuit of CCFL. As the piezoelectric transformer has a small size, high voltage gain, high efficiency, and superior insulation and is free of electromagnetic interference, it is usually used in the ignition circuit of a high light efficiency illumination system to achieve the characteristics of slimness, lightweight and superior electric performance.
In addition to increasing the size, increasing the area of the silver electrode is also a simple way to increase the output power of a piezoelectric transformer. However, increasing the area of the silver electrode will decrease the step-up ratio, which will affect the effect of increasing output power. Besides, increasing the size of a piezoelectric transformer also conflicts with the requirement of slimness and lightweight.